A common form of shallow draft vessel for use by sportsmen and fisherman in wetlands and estuaries is the pontoon boat. In practice, the pontoon boat consists of two parallel flotation pontoons, usually cylindrical in aspect, upon which is erected a flat platform deck and some form of railing to reduce the chance of the occupant from falling overboard. Such vessels are capable of providing very large working deck areas at relatively low cost and at relatively small draft. While the vessels are of limited seaworthiness, compared to a catamaran, they are relatively maneuverable at low speed and minimize draft for the amount of usable deck space provided. Various forms of such pontoon boats are known, including boats with enclosed cabins on the deck and various multi-passenger tour boats.
The relatively large platform size of such a pontoon boat makes the boat extremely unwieldy for over-the-road transportation when it becomes necessary to move the boat from one water location to another. Since pontoon boats are typically utilized in bayous and in tidewater wetlands, it is generally necessary to transport the boat over the road to a launching point.
For this reason, considerable effort has been spent in coming up with forms of collapsible or disassembleable pontoon boats which can be broken down to a readily transportable form and then built up to a usable structure at the point of launch.
For instance, U.S. Pat. No. 4,562,786 to Pruonto shows a collapsible pontoon boat, and specifically describes a pontoon deck assembly of removable panels. The patent delineates a specific structure of side rails for attaching and securing the deck panels to the pontoons. Passenger protective railing, erected on the deck, consists of a plurality of removable posts between which a lifeline is run. The resulting structure thus has a plurality of relatively small parts, and a relatively weak passenger protective railing.
U.S. Pat. No. 3,614,937 to Schulman shows a collapsible pontoon boat structure in which the pontoons are constructed in sections, abutted end to end, and interconnected by fastening to a continuous rail structure which forms a base of the deck section. Inasmuch as the entire strength and connectivity of the vessel is by means of an integrated deck structure, a removable deck panel structure would not be available with this form of construction.
Downing, U.S. Pat. No. 4,040,134, shows an eariler pontoon boat in which the individual pontoon sections are permanently affixed to a rigid deck structure, but may be folded over the structure to produce smaller external dimensions; the passenger protection rail structure, in the case of Downing, consists of individual removable side panels.
Other similar structures are shown for folding pontoon boats in U.S. Pat. No. 3,179,960 in which an X-shaped under deck structure provides the strength and rigidity permitting removble deck panels and removable pontoons to be interconnected to form a suitable boat, and U.S. Pat. No. 3,978,536 showing a boat that is foldable about a mid-deck hinge point running parallel to and between the pontoons.
Similar patents have shown various folding structures for use with catamarans or similar multi-hull vessels, including U.S. Pat. Nos. 4,223,621; 4,337,543; 4,662,297, and 3,608,112.
Each of the preceding structures has a significant disadvantage in that either the pontoon boat is maintained as an entity with certain sections folded inward to reduce dimension, but otherwise remains at full size, or the pontoon is shown as being disassembled into a relatively large number of small parts, all of which must be accounted for and maintained in order to provide for reconstruction of the vessel. In addition, set up time increases in direct proportion to the total number of components involved and the number of joints and interconnections decreases the reliability of the entire structure. In addition, most of the structures shown do not provide for sufficiently rigid passenger protection rails. Since pontoon boats are typically multi-passenger affairs and are often used for families, who will have small children aboard, the nature of the rail structure surrounding the platform deck is essential to safety.